Catheter is a medical device that can be inserted in a human body and used for a variety of purposes such as injection of medication or rinsing fluids, and so on. Particularly, it is important that an operator can control the catheter to a desired site in the human body with accuracy. To this purpose, U.S. Pat. No. 6,146,355 (Nov. 14, 2000) discloses a catheter of which an end is adjustable from left to right, or from right to left.
FIGS. 6A and 6B illustrate a catheter disclosed in U.S. Pat. No. 6,146,355. FIG. 6A is a top view of the catheter of the above-mentioned patent, and FIG. 6B is a cross sectional view of a lumen extrusion tip 320 of the catheter disclosed in the above-mentioned patent.
According to the US patent mentioned above, the catheter is manufactured by fusing a lumen extrusion shaft 318 of a relatively greater rigidity with a lumen extrusion tip 320 of a relatively less rigidity (see 318A). For reference, FIGS. 6A and 6B correspond to FIGS. 2A and 3C of the above-mentioned US patent, respectively, with the reference numerals in the drawings remain unchanged for convenience.
When using such conventional catheter, an operator rotates an adjustment dial 316 to one direction and pulls the wire 328 to one direction so that the lumen extrusion tip 320 of a relatively less rigidity is bent with respect to the lumen extrusion shaft 318. Accordingly, the catheter can be configured such that an end of the catheter is adjusted to left or right as desired.
Meanwhile, when the operator pulls the wire 328 of the conventional catheter to one direction, as illustrated in FIG. 7, due to tensile force of the wire 328, the lumen extrusion tip 320 of less rigidity is constricted in a diameter direction, resulting in upper and lower lumen openings 318BU, 318BL to deform in shape elliptically. This raises problems such as hindrance to injection of medication (or rinsing fluids), or to insertion of endoscopic device (not illustrated) which is blocked at the lumen openings 318BU, 318BL, rather than being inserted through the lumen openings 318BU, 318BL.